Shale gas extraction: The need to be seen to be clean

Natural-gas production is booming, but its green image is in question

Drill rigs tower over the silos on farms in Pennsylvania. Once-empty mesas in western Colorado, where mule deer and sage grouse ranged freely, now look like a neural network from a bird’s-eye view, with well-pads connected by dirt roads scattered across the landscape.

These are the signs of America’s natural-gas boom. Thanks to new drilling technology, and in particular a controversial process called hydraulic fracturing or “fracking,” the size of the proven reserves is growing. At the end of 2009 the United States had estimated reserves of 283.9 trillion cubic feet (8 trillion cubic metres) of natural gas, up 11% from the year before. In 2010 the country produced 22.6 trillion cubic feet of natural gas, up from 18.9 trillion cubic feet in 2005. The price at the wellhead has dropped from $7.33 per thousand cubic feet to $4.16 during the same period.

Natural gas is cheap and plentiful. That makes it an appealing alternative to wind and solar power, which are relatively expensive and erratic. And plants powered by gas emit far less carbon dioxide than those powered by dirty coal. Nearly half of America’s electricity is generated by coal, and electricity generation accounts for 40% of America’s carbon-dioxide emissions. In 2009, the most recent year for which data are available, the country’s greenhouse-gas emissions were at their lowest level since 1995. That was partly due to the bad economy, and partly to the increased use of renewables and natural gas.

But some question whether natural gas is really as green as all that. For one thing, fracking uses a tremendous amount of water, a severely undervalued resource inland. And the process gives off methane, a potent heat-trapper. A study led by Robert Howarth of Cornell University found that greenhouse-gas emissions over the life cycle of natural-gas production could actually be considerably higher than those of coal per unit of energy provided. Greater care about methane venting would, of course, reduce that problem.

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Activists and scientists reckon that if the process is safe, the companies should come clean. “If they’ve got nothing to hide, why is the industry so paranoid about disclosing their chemicals?” asks Steve Torbit, executive director of the National Wildlife Federation’s Rocky Mountain region. They may have to. The Environmental Protection Agency is studying the process. In 2009, House Democrats proposed legislation that would force the industry to disclose the chemicals it uses in fracking. Several states, including Texas and Colorado, have similar legislation pending.